The invention relates to a method and device for feeding cans to a continuous sterilizer provided with a moving chain with can holders for guiding the cans through the sterilizer.
In a continuous sterilizer containers, in particular cans, filled with a product (e.g. a food product) are subjected to a heat treatment (sterilization, pasteurization), the cans being exposed to a certain temperature for a certain period of time. In a continuous sterilizer cans are fed to the sterilizer and removed from the sterilizer continuously. The cans are generally fed in groups to the sterilizer, and are placed in groups in the successive can holders of the sterilizer. Loading of the can holders can take place through a group or row of cans being placed in the lengthwise direction next to a can holder and then being slid into the can holder transversely to the lengthwise direction of the group or row. It is also possible to fill a can holder in the axial direction by sliding a group or row of cans from one end of the can holder in the axial direction into the can holder.
The whole heat treatment process, incl. the supply of the cans to be treated and the discharge of treated cans, is dictated by the speed of the conveyor system of the cans into the sterilizer, since the residence time in the sterilizer is the determining factor for the entire process The cans must not in fact remain in the sterilizer for too short a period, since complete sterilization or pasteurization of the contents thereof then does not take place, or too long either, since this adversely affects the quality of the contents of the cans.
In the case of continuous sterilizers it is important that can holders are filled in the optimum way with cans, in order to achieve maximum utilization of the capacity of the sterilizer. This means that a joined-up group of cans with a predetermined number of cans per group must be present in each can holder. The number of cans per group must not be greater, in order to prevent the length of the group of cans from being greater than the length of the can holder, so that problems occur during filling of the can holders. The number of cans per group must not be smaller either, in order to prevent the can holders from not being completely filled. In addition, it is important for the space between successively infed groups of cans to be sufficient for placing each group of cans in a can holder. Finally, the groups of cans must be supplied in synchronism with the movement for placing the groups of cans in the can holders.
A problem here is that the cans come close together and in an upright position from a filling machine, at a slightly lower speed than the processing speed of the continuous sterilizer. These cans have to be fed at the correct speed and in measured quantities to the continuous sterilizer, taken from the upright position to the horizontal position, and divided into groups with a required minimum space between the groups.
Another problem occurring in practice is the stopping of the cans supplied at high speed, just before or while they are being inserted into the can containers. During braking of the supplied cans against stationary stops the cans are stopped suddenly and the cans bump against each other. Since the cans are not complete energy-absorbing bodies, cans can be flung back. Completely joined-up groups of cans are not then formed, while cans can also end up lying askew, which can lead to serious disruptions.